Clinical staging of upper urinary tract urothelial carcinoma for T staging: Review and pictorial essay

Abstract

Upper urinary tract urothelial carcinoma is staged using the TNM classification of malignant tumors. Preoperative TNM is important for treatment planning. Computed tomography urography is now widely used for clinical survey of upper urinary tract carcinoma because of its diagnostic accuracy. Computed tomography urography is recommended as the first‐line imaging procedure in several guidelines. Several reports stated that computed tomography urography is also useful for staging. However, no educational and practical reviews detailing the T staging of upper urinary tract urothelial carcinomas using imaging are available. We discuss the scanning protocol, T staging using computed tomography urography, limitations, magnetic resonance imaging, computed tomography comparison and pitfalls in imaging of upper urinary tract urothelial carcinoma. A recent study reported the high diagnostic accuracy of computed tomography urography with respect to T3 or higher stage tumors. To date, images that show a Tis–T2 stage have not been reported, but various studies are ongoing. Although magnetic resonance imaging has lower spatial resolution than computed tomography urography, magnetic resonance imaging can be carried out without radiation exposure or contrast agents. Magnetic resonance imaging also offers the unique ability of diffusion‐weighted imaging without contrast agent use. Some researchers reported that diffusion‐weighted imaging is useful not only for detecting lesions, but for predicting the T stage and tumor grade. We recommend the appropriate use of computed tomography and magnetic resonance while considering the limitations of each modality and the pitfalls in upper urinary tract urothelial carcinoma imaging.

Discrepancy between clinical and pathological T stages in upper urinary tract urothelial carcinoma: Analysis of the Hospital‐Based Cancer Registry data in Japan

“…In contrast, no effective T‐staging criteria for the differentiation of OC disease in UTUC patients have been reported. The current EAU guidelines note that it is difficult to distinguish ≤pT2 disease by the available preoperative imaging modalities 5,13,14 . The present findings showed that upstaging to ≥pT2 from ≤cT1 occurred frequently; the proportion of upstaging in the UCP and UCU patients was 30.7% and 34.2%, respectively (Fig.…”

Tumor heterogeneity evaluated by computed tomography detects muscle-invasive upper tract urothelial carcinoma that is associated with inflammatory tumor microenvironment

“…For more accurate assessment, a tumor mass should be evaluated directly by imaging examinations. CT and magnetic resonance imaging are the most common and useful examinations for a diagnosis of UTUC 10 , 11 . A tumor mass can be detected as a mass lesion with or without an irregular external surface on these images.…”

Conservative Treatment of Upper Urinary Tract Urothelial Carcinoma: Con

“…CTU shows high sensitivity and specificity of ≥92% in UTUC [5] . Unfortunately, CTU can only differentiate between T2 and T3 tumors with sensitivity and specificity of approximately 85%, with no certain differentiation between non–muscle-invasive (Tis/Cis, Ta, T1) and muscle-invasive (T2) tumors, which is essential for planning of conservative therapy [6] . In particular, flat lesions can escape detection, even by experienced investigators [6] .…”

“…Unfortunately, CTU can only differentiate between T2 and T3 tumors with sensitivity and specificity of approximately 85%, with no certain differentiation between non–muscle-invasive (Tis/Cis, Ta, T1) and muscle-invasive (T2) tumors, which is essential for planning of conservative therapy [6] . In particular, flat lesions can escape detection, even by experienced investigators [6] . Magnetic resonance imaging with the current protocols (sensitivity 75%) and positron emission tomography-CT (sensitivity and specificity between 80% and 85% [7] ) suffer from lower detection rates and are not recommended routinely [1] .…”